Plasma beam penetration of millimeter scale holes with high aspect ratios

ABSTRACT

An aluminum gas distribution plate refurbishment system combines a multi-beam inductively coupled plasma (AP-ICP) torch and vacuum discharge chuck. Plasma beams are employed to clean and restore to service the many gas flow passages in aluminum type gas distribution plates. Several parallel supersonic plasma beams of uniform density are produced from a single upper and lower AP-ICP plasma reactor arranged in totem pole that are driven by two pairs of opposing spiral planar RF induction RF antennas. These plasma beams are focused inside the gas flow passages to etch, heat, and deposit nanoparticles within. The vacuum discharge chuck includes a capacitively coupled plasma (CCP) reactor to generate a positive species discharge immediately beneath the gas distribution plates. This overcomes and undoes a Debye Sheathing effect, a electron-fed negative space charge blocking occurring above, and unknots any congested plasma beams in the gas flow passages.

FIELD OF INVENTION

The present invention relates to atmospheric pressure, inductivelycoupled plasma (AP-ICP) systems for semiconductor device processingequipment, and more particularly to plasma devices suitable forplasma-based refurbishment systems, tools, and methods to restoreworn/damaged aluminum gas distribution plates, aka showerheads, andreturn them to service.

BACKGROUND

The size of silicon wafers used in semiconductor and integrated circuitmanufacturing has grown in diameter now to 450 mm and beyond. Manyprocesses use plasmas generated from gases in clouds over the wafersurface to heat, etch, clean, rinse, and deposit materials on thesilicon wafers in dozens of steps to build hundreds, and even millions,of circuits across the surface of each wafer.

As the average diameters of the silicon wafers grew over time, it becameincreasingly more difficult to maintain process uniformities over theentire working surface. One such difficulty was in providing a uniformdischarge gas in which to induce a planar plasma. So thick gasdistribution plates that resemble water showerheads were developed thatincluded hundreds of small diameter gas flow passages to even out thedischarge gas across a wide area.

Unfortunately, these gas distribution plates were unavoidably beingexposed indirectly to the same processes the silicon wafers were, and sothe gas distribution plates were slowly being ruined by residualetchants and deposits. Wet-washing works well for the other affectedparts inside the processing chambers, but wet-washing cannot get insidethe gas flow passages because they are too narrow, e.g., on the order ofone millimeter.

Gas distribution plates are made from at least two alternativematerials, silicon ingot and aluminum billet. Each has a particularapplication. Applied Materials makes aluminum showerheads for PECVDdeposition processes, and these degrade with all the gas flow passageson a grid pattern being more or less equally contaminated with AlF₃.Tokyo Electron Ltd (TEL) makes silicon showerheads that are used inetching processes, these degrade because plasma ions bombard the processface and sputter material onto the outer edges. This degradation is notuniform, the worst damage concentrates around the outer periphery.Refurbishing involves reconstruction, in silicon, of the lost pieces ofthe inside walls of the gas flow passages around the periphery. Thesegas flow passages are set in radial patterns.

Both aluminum and silicon gas distribution plates are very expensive toreplace, so refurbishing them makes good economic sense.

These large gas distribution plates have gas flow holes that piercecompletely through. These high aspect through-holes are relatively smallin diameter, compared to thickness of the gas distribution plate itself,for example a 0.062″ diameter hole through a 1.2″ thick plate.Maintaining the original hole geometry of all the gas flow passages isvery important.

During various PE-CVD processes involving aluminum showerheads, theseholes can get eroded and clogged. Most of the volatile by-productstypically produced during reactions get pumped out from the chamberthrough an exhaust system. But enough residue remains on the surface ofthe gas distribution plate and inside the gas flow passages toeventually cause trouble. Eventually the entire gas distribution platehas to be scrapped, not repaired, because there has been no conventionalway to restore them.

The cost of materials and manufacturing of gas distribution plate issubstantial. So it would be advantageous to increase the lifetime of gasdistribution plates by protecting them from plasma chemical corrosionwith special coatings. But a means has yet to have been develop wheregas distribution plates can be efficiently and cost effectivelyrefurbished. Moreover, as the size of the next generation gasdistribution plates is increasing to accommodate next generationprocessing wafers in excess of 1.2 square meters, a solution becomesincreasingly important.

What has been holding everyone back is a well-known Debye self-shieldingeffect that ordinarily blocks plasma beam penetration of millimeterscale passages, grids, and holes. Plasmas thus have a characteristiclength, known as a Debye Length, which can be represented by,

L(cm)=743(Te/ne)exp(0.5)

where Te is the electron temperature in eV, and ne is the electrondensity in electrons/cm³.

Typical high-density atmospheric pressure ICP plasmas have a density of10 exp(14)/cm³. High density supersonic plasma beams have a relativelylow electron temperature of around 0.04 eV. Therefore the Debye Lengthfor these can be computed to be around five millimeters. Well short of1.2″ needed to pass through a typical gas distribution plate.

Through-holes that are shorter than the Debye self-shielding length willcause an electron congestion that impedes plasma beams from completelypenetrating intact. The Debye blocking forms from a negative sheathlayer that appears inside the gas flow passages and is continuallycharged by charged particles stripping off the plasma beams trying topenetrate. Conventional wisdom has been just to accept this limit as agiven and work some other approach.

Plasma-based refurbishment systems and tools are needed more than everthat can effectively clean and restore both silicon and aluminum typesof gas distribution plates to service. In spite of the Debye blocking.

SUMMARY

Briefly, an aluminum gas distribution plate refurbishment systemembodiment of the present invention combines a multi-beam inductivelycoupled plasma (ICP) torch and vacuum discharge chuck. Plasma beams areemployed to clean and restore to service the many gas flow passages inaluminum gas distribution plates. Several parallel supersonic plasmabeams of uniform density are produced from a single upper and lowerAP-ICP plasma reactor arranged in totem pole that are driven by twopairs of opposing spiral planar RF induction RF antennas. These plasmabeams are focused inside the gas flow passages to etch, heat, anddeposit nanoparticles within. The vacuum discharge chuck includes acapacitively coupled plasma (CCP) reactor to generate a positive speciesdischarge immediately beneath the gas distribution plates. Thiscounteracts a congestive effect of Debye sheathing, which is anelectron-fed negative space charge blocking. The CCP plasma reaches into diminish the impediment to the intact penetration of the plasma beamsthrough the gas flow passages.

SUMMARY OF THE DRAWINGS

FIG. 1 is a schematic diagram of a linear, multi-beam atmosphericpressure, inductively coupled plasma (AP-ICP) torch and vacuum dischargechuck embodiment of the present invention that simultaneously ejectsseveral plasma beams in parallel in a single row to clean and restorealuminum billet gas distribution plates to service;

FIGS. 2A, 2B, and 2C are cross-sectional front view diagrams of thewedged nose area involving eight-nozzles in AP-ICP torch of FIG. 1.Eight plasma beams are produced in a 1×8 linear array. Electronicfocusing is implemented with an extractor. Gas sealing is provided bylid. A CCP auxiliary CCP discharge is generated inside the vacuumdischarge chuck. A parasitic capacitance C_(par) is symbolized here withfloating voltage V_(f) appearing in an electron congestion heaped insidebehind each nozzle's orifice, and the electron focusing effects ofelectric field E_(b) relative to the base voltage V_(b) on the extractorplate;

FIGS. 2D, 2E, and 2F are exploded assembly perspective view diagramsillustrating how the eight-nozzle wedged nose of the ICP torch of FIG. 1and FIGS. 2A, 2B, and 2C could be assembled together by a glassblowerand fused-welded in a practical way;

FIG. 3A is a perspective view diagram of the specialized single AP-ICPplasma torch of FIG. 1 with two opposing pairs of spiral planar RFinduction RF antennas, and an eight-nozzle output for eight parallelsupersonic plasma beams of uniform density in an embodiment of thepresent invention. The upper pair of planar RF antennas are fed a lowerRF power at a different frequency and have wider spacings betweenwindings where they cross laterally over the middle than those samewindings do when gathered at their left and right edges;

FIG. 3B is a schematic diagram of the front and back branch antennasassociated with the upper confinement tube of FIG. 3A and to illustratea spacing dimension “D1” and a spacing dimension “D2” representing gapsbetween adjacent windings;

FIG. 4A is a cross-sectional view diagram of the single AP-ICP plasmatorch of FIGS. 1-3 without showing the two opposing pairs of spiralplanar RF induction RF antennas. The injection and flow of sheath gas atthe top and bottom flanges joining the upper and low quartz confiningtubes is best seen in this view;

FIG. 4B is a perspective view diagram of the Teflon top flange of FIG. 1which inserts like a bottle stopper into the upper quartz confining tubeof FIG. 4A;

FIG. 4C is a perspective view and exploded assembly view diagram of thesingle AP-ICP plasma torch of FIG. 4A with cutaways of the Teflon bottomflange and lower quartz confining tube, and further includes in view theTeflon top flange of FIG. 4B. This view of FIG. 4C provides a morerealistic approximation of what is required of a glassblower in theconstruction of the plasma beam nozzles and flow diversion archesnecessary to impart the non-turbulent flows necessary to promote uniformplasma densities in the several plasma beams;

FIG. 5 is a perspective view diagram looking from below up into thesingle AP-ICP plasma torch of FIG. 4C and with the lower pair of planarRF antennas. This and the view of FIG. 4C provide a more completeunderstanding of what is required of a glassblower in the constructionof the plasma beam nozzles and flow diversion arches necessary to impartthe non-turbulent flows necessary to promote uniform plasma densities inthe several plasma beams. The near side of the lower quartz confiningtube is normally closed, it is shown here open for purposes ofillustration only;

FIGS. 6A to 6E are cross-sectional diagrams that represent the variousstages of a Debye Layer build up in a gas flow passage and how thepositive species auxiliary plasma from a CCP reactor underneath can suckout the fallen halo electrons to reestablish a plasma carrier;

FIG. 7 is a schematic diagram of a twenty nanometer diameternanoparticle being pre-melted at 600° C., liquefied at 1200° C., andfinally vaporized at 2000° C., as occurs in the top and then the bottomplasma reactors;

FIG. 8 is a cross-sectional view diagram of the vacuum discharge chuckof FIG. 1 and shows a gas distribution plate installed forrefurbishment. “D” is the z-axis distance from the extractor necessaryto put the gas distribution plate in the focal plane of the plasmabeams, and “d” is the z-axis gap between the gas distribution plate andthe copper mesh necessary to establish and maintain the auxiliary CCPdischarge without electrical arcing;

FIG. 9A is a schematic view diagram of dielectric barrier discharge lineof FIG. 1 with a representative inflow of incoming nanopowder clusterson the left and a de-aggregated outflow of these nanopowders on theright. The same dielectric barrier discharge line is also used todisassociate molecular hydrogen gas (H₂) into atomic hydrogen gas (H)for its use as a discharge gas in the single AP-ICP plasma torch ofFIGS. 1, 2, 3, 4A, and 4C;

FIG. 9B is a cutaway perspective view diagram of the dielectric barrierdischarge line of FIGS. 1 and 9A with the addition of an argon supply tokeep nanopowder from depositing on the sixteen needles;

FIG. 10 is a flowchart diagram of a method of refurbishing aluminum gasflow distribution plates with the equipment illustrated in the precedingFigs.;

FIG. 11 is a simplified perspective view diagram of the vacuum dischargechuck of FIG. 8 which has turned and x-y positioned the gas flowdistribution plate in its top to be properly addressed by the lineararray of plasma beams produced by the single AP-ICP plasma torch.Several other pieces, like the sealing lid 106, are omitted from thisillustration to better show such addressing of the gas flow passages;

FIG. 12 is a schematic diagram of the nanopowder input processing from ananopowder package, a punchers, a three-way valve, a cloud generator, aturbo-pump, and finally delivery in a nanopowder cloud to the dielectricbarrier discharge line of FIGS. 9A and 9B for de-aggregation ofclusters;

FIGS. 13A-13C perspective view diagrams in cutaway of the nanopowdercloud generator of FIG. 12. FIG. 13C shows the nanopowder cloudgenerator in a “normal” vertically standing orientation in which theimpeller shaft is at the top and a nanopowder well is down at thebottom. A rocker-shaker, heater, and vibrator (not shown) tilt thebottom up in a rocking motion, while vibrating and heating to keepnanoparticles from clumping or sticking on the inside surfaces;

FIG. 14 is an exploded assembly view in perspective of a nanopowderpackage puncher as first mentioned in FIG. 12;

FIGS. 15A-15E illustrate the use of a modified Bosch Process to repairthe outlets of gas flow passages in silicon gas distribution plates. Theconventional Bosch Process applies a passivation layer in repeated stepsinterdigitated with anisotropic etching steps. Embodiments of thepresent invention deposit silicon from vapors instead of the passivationlayer;

FIGS. 15A-15C are cross sectional view diagrams of a three-step cycle ofsilicon deposition, anisotropic etching, and annealing/bonding;

FIG. 15D is cross sectional view diagram show how a sliding movement ofthe gas distribution plate is accommodated to treat a next gas flowpassage;

FIG. 15E is a cross sectional view diagram showing how an argon glow atthe outlets of gas flow passages in silicon gas distribution platesunder the plasma beam can be used as a visual indicator of properalignment;

FIG. 16 is a perspective view diagram of a focused plasma systemembodiment of the present invention that generates a single plasma beamfor refurbishment of silicon gas distribution plates; and

FIG. 17 is a functional block diagram of a two-part AP-ICP showerheadrefurbishment system with a deposition part, and an etching-annealingpart, that share a program controlled five axis motion system.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention overcome a phenomenon in whichfocused plasma beams fail to fully penetrate millimeter widethrough-holes, like the holes plasma torch nozzles, and the gas flowpassages in gas distribution plates. The phenomenon occurring in thesesmall geometries is generally known as the Debye Sheathing Layer and theDebye Length is depth in which the congestion develops. Small millimeterwide passages will cause an electron congestion to accumulate fromelectrons that strip off the plasma beams and stick inside the walls.The electron loses destabilize the equilibrium the focused plasma beamsonce had, and positive ions fall out as well. Only the neutrals getthrough past the congestion. The plasma beam is thereby renderedincapable of transporting etchants or nanopowders deep inside the fullpassage length.

The present inventors discovered a way to breach the so-called Debyelimitation by generating an auxiliary capacitively coupled plasmadischarge in the immediate vicinity of the gas flow passage exits. Thepositive plasma species ionizes the neutral particles in the supersonicplasma beams that did not interact with the Debye layer. As a result,these reach the gas flow passage exits. The ions from the positiveplasma species are attracted by the negative Debye sheath charge on thegas flow passage walls and penetrate from the backside, opposite to thebeam direction. Such quench the Debye charge.

The plasma beam's potential equilibrium is restored, and the way isclear to proceed with refurbishment treatment processes.

Embodiments of the present invention overcome these challenges and morewith a two-stage atmospheric pressure, inductively coupled plasma(AP-ICP) torch with a linear array of millimeter wide nozzles that ejectseveral plasma beams in parallel.

A first instance of Debye blocking occurs inside each nozzle becausetheir orifices are only a millimeter in diameter. The electroncongestion is overcome by an extractor plate in front of each nozzlethat draws out and drains the electron accumulations.

A second instance of Debye blocking occurs just inside each of themillimeter diameter gas flow passages in a gas distribution plate. Thisinstance of congestion is overcome by situating an auxiliary CCPdischarge plasma at the exits of the gas flow passages, beneath the gasdistribution plates. A positive plasma species is generated by a CCPdischarge in argon gas just above a copper mesh.

Both of our solutions work because they draw electrons out of the holesfrom the exit sides and relieve the congestion so the plasma beams canproceed unimpeded to do their work.

FIG. 1 represents a top-level overview of a multi-beam atmosphericpressure, inductively coupled plasma (AP-ICP) torch and vacuum dischargechuck system 100. Further details of each part follow in theillustrations that follow FIG. 1.

System 100 is capable of etching, cleaning, rinsing, heating, coating,and annealing the insides of several hundred gas flow passagesconstituent to an aluminum gas distribution plate (GDP) workpiece 102.As such, system 100 is capable of refurbishing and returning GDP's touseful service in various kinds of semiconductor processing equipment.

Here, GDP workpieces 102 are made from aluminum billet as is typical ofApplied Materials (Santa Clara, Calif.). In the case of aluminum billet,worn GDP workpieces 102 will be usually contaminated with AlF₃ films.Hydrogen based plasmas are known, and used herein, to to clean away AlF₃films on aluminum gas distribution plates. The linear system 100 of FIG.1 is used for these because several plasma beams are simultaneouslyemployed.

In the case of silicon gas distribution plate, the degradation will havebeen caused from exposure to processing etchants to only a few outletsconcentrated around the periphery on the process face. A single focusedplasma beam 1600 is used in this application, as illustrated in FIG. 16,and a Modified Bosch Process is employed to rebuild the silicon lost toprocess etchants. The Modified Bosch Process presented step-by-step inFIGS. 15A-15E.

The GDP workpieces 102 are held in position by a vacuum discharge chuck104. A motion system underneath and another attached to the plasma torchget things lined up. Too much gas leakage would occur if the severalhundred gas flow passages in the GDP were left exposed, so the vacuumdischarge chuck 104 operates a pop-up/press down lid 106 to seal GDPworkpieces 102. The vacuum discharge chuck 104 lifts on the z-axisrelative to a electrode extractor plate 108 to bring the gasdistribution plate workpiece 102 into the focal plane of a plasma beamarray 110 and its several parallel plasma beams 111.

Each plasma beam 111 is shaped by a respective nozzle 112 that isglass-formed as a one millimeter diameter orifice in the wedged nose ofa lower quartz confining tube 114. The constituent parallel plasma beamshave a regular pitch between them that matches the pitch between gasflow passages in GDP workpiece 102, e.g., 5.0 mm or 10.0 mm. Eachrespective nozzle ejects a supersonic flow of plasma in a focused beamwith an assist from the electric field effects of extractor plate 108.

A pair of spiral wound, planar RF antennas, lower RF antennas 116 and117 are placed immediately front and back of the lower quartz confiningtube 114. An air gap of about one millimeter between the glass and theRF antenna windings is preferred. When RF power is applied, a vaporizingplasma forms between in discharge gases selected and delivered underpressure from above.

A Teflon flange 118 connects an outside bottom end of an upper quartzconfining tube 120 to inside the top of lower quartz confining tube 114.Teflon flange 118 injects a sheathing gas 122 under pressure all aroundand surrounds what feeds down into the lower quartz confining tube 114from above. Such sheathing gas keeps the hot plasma away from the quartzconfining tube to prevent overheating and damage. Various experimentsand prototypes suggest that the finished gap for the bottom sheath gasinjected between the outside bottom of upper quartz confining tube 120and the inside top of lower quartz confining tube 114 should be about0.25 mm. This positioning is maintained by Teflon bottom flange 118. Andthe bottom sheath gas 122 is supplied under pressure to gas nipples onthe left and right sides.

A pair of spiral wound, planar RF antennas, upper RF antennas 124 and125 are placed immediately front and back of the upper quartz confiningtube 120. Under power, a pre-melt plasma forms between inside that isfed discharge gases under pressure from above. The coil windings ofupper RF antennas 124 and 125 are spaced further apart horizontally thanthey are vertically. That is, the coil windings on the left and rightedges looking broadside (as in FIG. 1) are tighter together. This isintended to induce more of the RF power into the left and right edges ofthe plasma ball that gets induced between. The object of that is to makethe several plasma beams 111 uniform in plasma density.

Our two-stage plasma generation, in the upper and lower quartz confiningtubes 120 and 114, allows much lower RF powers to be applied to RFantennas 124, 125, 116, and 117. An advantage of that is no arcingbetween RF antenna windings, and better plasma uniformity across plasmabeam array 110.

Conventional AP-ICP plasma torches eject a single plasma beam that iscoaxial with a concentric AP-ICP coil wound around the outside of anopen ended quartz electrode. But such an arrangement is unsuitable herebecause that single plasma beam would get squeezed by an annularmagnetic field. Such a coil arrangement would not allow a spread ofseveral parallel plasma beams in a wide linear array.

A Teflon top flange 130 stoppers the top end of the upper quartzconfining tube 120. See also FIG. 4B. Inside the top end of the upperquartz confining tube 120 Teflon top flange 130 curves up in the middlefrom both sides along its bottom in an arc that matches that of the topwinding of upper RF antennas 124 and 125. The two rounded arches runimmediately adjacent to one another, one inside and the other outsideupper quartz confining tube 120. The purpose of this is to be able toquickly and efficiently light a plasma in a discharge gas at startup.

The curvature of the top Teflon flange and the curvature of the topwinding outside turn of the RF antennas should match to help develop aconsistent gap between a frontal sheath gas injection layer and the highvoltage potential line at the top wire. The object is to induce asimultaneous breakdown of the sheath gas layer in a wide arc. Such adischarge should be uniform in starting the AP-ICP discharge. Afterinitiation, the AP-ICP discharge density will be proportional to the RFpower distribution. E.g., high in the left-right periphery, and low inthe center. This is opposite to what occurs in the bottom RF antennabecause of the different way those are wound.

Three rows of nipples/injectors run across the top of Teflon top flange130. The middle row provides for a uniform injection of nanoparticles132 through several capillaries each modulated by a mass flow controller134. The front and back rows of nipples/injectors are used to insert adischarge gas 136 and an upper sheath gas 138 around the plasma formed.The discharge gas fuels the plasma and the sheath gas jackets the plasmaand keeps the quartz confining tube from being touched by the plasma andoverheated.

Seed electrons from a high voltage source like a Tesla ignitor coil areused to initiate the top reactor's plasma. A tungsten wire from theTesla Ignitor Coil is run inside through one of the sheath gascapillaries in the Teflon top flange 130. Under power, a sharpened endof the tungsten wire ejects seed electrons that spread in the gas flownear the top winding of RF antennas 124 and 125. This spot is subject tohigh high voltage potential and high electric field. Once ignited, morethan enough seed electrons fall down into the bottom reactor forignition of that plasma.

A dielectric barrier discharge line 140 uses RF power to (1)de-aggregate nanoparticles 132, and alternatively, (2) to disassociatemolecular hydrogen gas (H2) into atomic hydrogen gas (H). These are twodifferent jobs.

If fully de-aggregated, nanoparticles will melt at a much lowertemperatures than the bulk materials do. Fully de-aggregated, the upperplasma reactor can do it job of pre-melting the nanoparticles much moreeffectively.

A typical nanoparticle 132 that system 100 would use to coat the insidesof gas flow passages in gas distribution plates is Yttrium OxideNanopowder (Y₂O₃, 99.99%, 10 nm), as supplied by US ResearchNanomaterials, Inc. (Houston, Tex.). The Nanopowder cloud generators andpackage punchers of FIGS. 13A-13C, and 14 may also be needed tointroduce nanoparticles 132 in a cloud into system 100.

Pressure inside the plasma cavity is sealed by a flexible lid 106 with asingle group of holes aligned with the plasma jet for exposing to theplasma beam to a single group of passages 103. Sealing lid 106 ismaintained on the platform by a drop mechanism. It is only lifted forrepositioning and alignment with the GDP workpiece 102.

A reverse-direction penetration by the auxiliary plasma discharge intothe gas flow passages 103, through the exits, occur due to an attractionof the Debye sheath layer itself. Two-sided plasma etching (from boththe entries and exits) requires an injection of HCl gas into the plasmachuck, and ionization by the CCP discharge. The Debye phenomenon is usedby us to assist with uniform etching of gas flow passages 103.

FIGS. 2A, 2B, and 2C illustrate the complex structures and plasmainteractions involving the formation, and flows dividing into plasmabeam array 110. Eight parallel, uniform density, plasma beams 111 arerepresented here as being supersonically ejected from respectivemultibeam nozzles 112.

FIG. 2B details what happens inside and behind each multibeam nozzle112. A plasma flowing down within lower confinement tube from the AP-ICPreactors above divides in a combing action around rounded arches 209 andcongests equally inside eight sinks 210 to form eight respective plasmabubbles 212. Electrons from the plasma flowing down inside congestinside the sinks 210 around multibeam nozzles 112 into an “electroncongestion” 214. A Debye Sheath effect develops here, as would beexpected with a one millimeter orifice. The congestion hinders andimpedes the ejection of each plasma beam 111.

The congestion caused by electrons gathering together, produces afloating charge Vf with relation to extractor plate 108. Electric fieldsgenerated by the close proximity of extractor 108 attracts electrons todrain out through nozzle 112 and permit the ejection of plasma beams111. Such drainage is a leakage current across parasitic virtualcapacitor, C_(par), that varies with the RF power applied and plasmadensity.

The congesting plasma bubbles 212 within plasma sinks 210 helps restorea laminar plasma flow in the emission of plasma beams 111. A smoothconvex surface placed across rounded arches 209 also helps to reduceturbulence.

As best seen in FIGS. 2D-2F, the bottom end of quartz confining tube 114tapers, front and back, into a multiport nozzle wedge. The style of thisis a variance of what is shown in FIGS. 2A-2C. One supplier for aprototype formed these rounded arches 209 from wedge half sections ofglass tubing, and one millimeter diameter graphite rods were pressedinto the molten glass to make the orifices for each nozzle.

Referring especially to FIG. 2B, the plasma flowing down inside lowerconfinement tube 114 from the two AP-ICP reactors above is ideallydelivered here in a laminar flow of uniform density across its width.This plasma is under some pressure and its materials and energy must bedivided amongst multibeam nozzles 112 with as little disturbance to theflow as possible.

A number of convex rounded arches 209 are fabricated between respectiveconcave smooth rounded sinks 210. These evenly “drain” the dividedplasma directly out through each orifice in corresponding multibeamnozzles 112.

The electron congestion 214 is a virtual electrode with a floatingcharge V_(f) relative to V_(b) at extractor plate 108. A virtualcapacitor C_(par) thus formed is employed to leak off the electroncongestion 214 and pull plasma beams 111 from the plasma bubbles 212.

These Debye layers behind the nozzles are characterized by a floatingsurface potential V_(f) (in FIG. 2A-2C) that increases with increasedplasma density. The plasma beams attempting to penetrate the tiny nozzleorifices will charge the inside surfaces to a threshold value. At somethreshold value of plasma density, a floating potential V_(f), can buildup enough to significantly impede the plasma flow through the onemillimeter orifices. The plasma density is a function of the RF powerapplied to the RF antennas above and how much is consumed by the plasmadischarge.

If the highly pressurized, high temperature flows of plasma beams getsstalled, its positive ions can accumulate in plasma bubbles, and squeezeout any sheathing gas coolant flows. The multibeam nozzles 112 andconfinement tube 114 can then overheat, melt their quartz walls, and caneven cause the linear beam system itself to explode.

Electron lensing with extractor 108 is useful to vary the focus depth ofelectron streams. For example, like those emitted by cathodes with avoltage potential that develops like a leaking current through a leakresistor. In other applications, making such leak resistances variableallows for adjustments in the bias potential on the electrode, andchanges of the electron current density of an electron gun.

The electrode biasing phenomenon is advantageously applied here to theseatmospheric plasma beams 111. Extractor plate 108 is drilled with amatching group of 1.0 mm to 1.5 mm holes. These are aligned with themulti-nozzle orifices, e.g., on a pitch of 5.0 or 10.0 mm. Each electroncongestion 214 developed by the Debye layer inside each orifice becomesits own electrode. A parasitic capacitive coupling C_(par) (FIG. 2B)interacts between each orifice as aligned with each hole facing it inthe extractor 108.

Such virtual parasitic capacitor C_(par) coupling can be used todischarge a floating voltage V_(f) on the electron congestion and theDebye layer. Parasitic capacitor C_(par) increases in value withdecreases in the Z-gap between the orifices of the mini nozzles and theholes of the extractor. Electron guns have a DC leaking current, herethe displacement current is AC and depends only on the impedance ofparasitic capacitor C_(par). Control can thus be realized by physicallydecreasing the Z-gap to increase C_(par), for an increase in the ACdisplacement current, as well as increase a bias potential V_(b),between each orifice and the edges of its corresponding extraction hole.

A bias voltage of V_(b) can lower the floating voltage V_(f) and,therefore, increases the improved permeability through the Debye layer.The increase can be enough to liberate the plasma beams from clotted andallow them to eject. The bias voltage further creates an electricalfield E_(b) in the center of the extraction holes, and functions here asan electron lens.

In summary, a grounded copper extractor plate 108 with holes positionedto act as lenses functions to liberate plasma beams across a gap thatwould otherwise be blocked inside the mini nozzles and extracts theminto focused plasma beams from the orifices. Controlling the gap can beused to bring tight focus on the surface inlets of gas flow passages 103in a gas distribution plate positioned just beneath the extractor.

Moving a discharge chuck holding the plasma distribution plate in thesame Z-axis can also manipulate the focal plane. The crossovers of theplasma beams and minimal deposition spots can be provided exactly inthese inlets to increase plasma beam penetration and efficiency insidegas flow passages 103.

If the bottom wires of the bottom RF antennas 116, 117 are too close tothe grounded copper extractor 108, their mutual coupling can cause aelectromagnetic field interaction with the extractor 108 and inducecurrents around the extractor holes. Such currents, if concentrated nearthe edges of the holes, can create their own potential V_(i) andelectric field E_(i) that are coincident with a biasing field E_(b) anddrastically magnify the extracting and focusing properties of theextractor.

Unfortunately, such effects are not uniform. The non-uniformity causesdensity variations between the plasma beams at their respective inletareas, and thus result in different rates of nanoparticle deposition. Tocombat this, the diameter of the extractor holes can be varied from themiddle to the sides. Other tricks too can be included to produce uniformnanocoating of the inner surfaces of the gas flow passages 103 of thegas distribution plate.

An auxiliary CCP discharge plasma 200 is generated inside the vacuumdischarge chuck 104, and between the GDP workpiece 102 and a copper mesh202. This space is filled with argon as a discharge gas flowing frombelow and up through the copper mesh 202. Between these an RF power isapplied in a capacitively coupled plasma (CCP) arrangement. Severalreverse direction penetrating plasma beams 204 result that reach up andsuck out electrons in Debye Layer accumulations that form inside the gasflow passages 103 103 inside the GDP workpiece 102.

The top and bottom RF antenna pairs are similar. The top RF antenna pairdrives a low-power top plasma reactor responsible for pre-heatingetching gases and pre-melting nanoparticles. The reactor heats anddissociates the radicals in the etching gases and vaporizes thenanoparticles.

Such RF antennas generate a transverse RF magnetic field free of anaxial RF magnetic field component and related RF power losses due toaxial leaking. Conventional axial RF magnetic fields would produce amagnetic lens here that would gather the charged plasma species around asingle axis of the reactor into a narrow filament. The broad hightemperature area needed for vaporization of the injected in plasmadischarge would be overly narrowed.

The high temperature area available to vaporize the Y₂O₃ nanoparticlesand dissociate the etching gases cannot be too narrow. Thosenanoparticles that miss the high temperature area along the reactor axiswould not be melted and could cloud the etching gases with dust. Thedust clouds would also easily contaminate the etching and coatingprocesses.

As seen in FIG. 16, saddle RF antennas with transverse RF magneticfields can put all the applied RF power in a RF magnetic field normal tothe reactor axis in a radial spread. Such RF antennas are able to launchand sustain plasma discharges from the periphery, not from only thecenter. A uniformly distributed plasma density across the reactorexpands the high temperature area enough to capture and vaporize all thenanoparticles.

Each RF antenna pair is mirrored in front and back pairs with an equalnumber of the turns that envelope the outer wall of the reactor. Theresulting magnetic fields pierce each cylindrical layer of the gasvolume in the plasma reactor and induce plasma discharges.

Connecting RF antenna pairs in parallel reduces the overall impedance ofthe load. The required RF power is reduced and as is the cost of the RFpower components. The RF power that is applied through the inductivecoupling to the RF antenna on each side is enough to sustain and heatthe plasma discharge in between.

At some level of RF power, the plasma discharge can be pressed into aplasma ball. The top RF antennas are are operated at 27.12 MHz and at anRF power of about 2.5 kW. Five winding turns for each pair were found tobe optimal for a reactor diameter of about twenty millimeters. Thislevel of RF power and RF antenna winding geometry allows a RF plasmaball to be obtained with diameter around sixteen millimeters. The powertransferred to plasma can increase the plasma density (ne) up to about10e19 cm³ and can reach a maximum temperature (Te) of about7,000-10,000° K.

A conventional impedance matching network from Comdel (Gloucester,Mass.) is used to couple respective RF generators to each RF antennapair. An over-pressure in the high temperature plasma ball pushes out ahigh temperature supersonic torch downstream. Such torch serves as acarrier for the nanoparticle vapors.

FIGS. 2D-2F suggest a way that the wedged nose and nozzles of FIGS.2A-2C could be constructed. E.g., of quartz glass parts that are fusedor otherwise welded together by a glassblower in a finished assembly. Asmooth, even division of the plasma from above into eight plasma beams111 can be had by arranging several wedge sections of glass tubingrounded arches 209 in a single row. These should also be equally spacedand evenly distributed across the width of the wedged nose. Orifices formultibeam nozzles 112 are formed by various conventional methods betweenadjoining rounded arches 209.

FIG. 3 represents a novel arrangement of induction antennas in anatmospheric pressure inductively coupled plasma (AP-ICP) torch 300. Suchwas necessitated by the need to produce an array of plasma beams 110 inwhich each beam 111 is uniform in density. The pair of upper RF antennas124 and 125 are spiral wound planar types. Their wires are arranged inparallel very close to upper quartz confining tube 120. These have acharacteristic wind to their coils that increasingly varies between 1-5mm in spacing vertically between windings at the middle of thehorizontal crossings, and a constant one millimeter spacing horizontallybetween those same windings at the left and right edges.

The purpose of this winding characteristic is to induce a plasma insidebetween them that spreads in uniform density between the left and rightedges. This strategy can also be employed to compensate fornon-uniformities elsewhere. Antennas 124 and 125 are wired in parallelto present a lowered load impedance Z_(L) that will discourageinter-winding arcing. In furtherance of this goal, RF antennas 124 and125 are fed a relatively low RF power by RF generator 301, matchingnetwork 302 and bridge network 302.

The pair of lower RF antennas 116 and 117 are also spiral wound planartypes wires and also arranged in parallel, again very close to lowerquartz confining tube 114. These have a characteristic wind to theircoils with a constant 4-5 millimeter spacing horizontally and verticallybetween the windings. The purpose of this is to allow medium level RFpowers to be applied without arcing. Antennas 116 and 117 are wired inparallel to present a lowered load impedance Z_(L) that will discourageinter-winding arcing. Antennas 116 and 117 are fed a medium level of RFpower by RF generator 306, matching network 308 and bridge network 310.RF generators 301 and 306 operate at different frequencies to reducecrosstalk and coupling between the upper and lower RF antennas.

A single pair of RF antennas could be driven by high RF power, but theresulting plasma delivered across array 110 would not be as uniformlaterally as is needed, and arcing across the windings would be aproblem.

FIGS. 4A, 4B, and 4C all relate to an assembly 400 of the upper quartzconfining tube 120 and lower quartz confining tube 114, and how theupper quartz confining tube 120 is stoppered by Teflon top flange 130.The upper quartz confining tube 120 and lower quartz confining tube 114are flanged together with Teflon bottom flange 118. An important job forboth flanges 130 and 118 is to even the distribution and insert adownward flowing and uniform sheath gas. This sheath gas flows in ajacket tight up against the inside walls of lower quartz confining tube114.

Teflon bottom flange 118 must also hold and maintain a 0.25 mm gap allaround between the outside bottom end of upper quartz confining tube 120and the inside top end of lower quartz confining tube 114. The sheathgas jacketing must by necessity be very thin, otherwise unwanted anddamaging parasitic plasmas can develop in the sheath gas as it passesimmediately in front of each of the faces of RF antennas 124, 125, 116,and 117.

The bottom sheath gas flow has three functions: a) charge neutralizingof the deposits on the inner surfaces of the bottom confining tube, b)cooling of the inner surface of the bottom confining tube, and c)fueling the bottom discharge.

The quartz confining tubes, in both the upper and lower reactors, arewindows transparent to the RF magnetic field energy generated in the RFantennas. This arrangement presses the discharge plasma into a hightemperature plasma torch that can melt and vaporize nanoparticlesinjected by capillaries attached to the Teflon top flange 130.

Nozzles 112 are set along the distal bottom edge of confining tube 114in a converging angle of about 55°. The goal is to maintain a laminarflow in the plasma stream through a restrictive throat of about onemillimeter. The converging geometry rapidly compresses the hot plasmawith minimal turbulence and heat losses while maintaining the plasmastream's laminar flow. Pressures inside the plasma reactor areproportional to the RF power being applied to the RF antennas. Theapplied RF power is optimized to produce a sonic flow of plasma specieswhich can carry the vaporized nanoparticles. The RF power applied alsostrongly affects aerodynamic focusing and deposition rates. The optimalaerodynamic focusing of the generated plasma beam is characterized by alow divergence angle and a minimal crossover δ at a reasonabledeposition rate of around two micrometers per second.

With reference to FIGS. 4A, 4C, and 5, the typical distance between eachorifice in each nozzle 112 and its respective extractor hole 108 isabout one millimeter. This is so an electric field will develop betweenthe negatively charged orifice and the grounded extractor. The nozzleitself provides some aerodynamic focusing but with a large convergenceangle. The extractor 108 sharpens the focus, like a short electron lens,to a plasma spot of about 0.1 millimeter at some focal plane. This spotis small enough for the plasma beams of array 110 to penetrate theinlets and get down deep inside the gas flow passages 103.

FIG. 5 shows a practical way of glass blowing 500 to implement multibeamnozzles 112 in the bottom end of lower quartz confining tube 114. Here,the sides of the tapered nozzle are shown open, but that is only forpurposes of this illustration. The whole bottom end of lower quartzconfining tube 114 tapers (front and back) into a wedge with asaw-toothed edge to bring the plasma inside down to a point forsupersonic ejection from several orifices in an array that can each beas small as one millimeter in diameter.

Our theory on how plasma beams 111 in array 110 penetrate the gasdistribution plate passages is laid out in steps over FIGS. 6A-6E. Aprecise alignment of the discharge chuck relative to the plasma beam isrequired as a precondition. The axis of a gas flow passage must bebrought into coaxial alignment with the axis of a corresponding plasmabeam 111. The design of plasma chuck 104 must accurately provide forsuch adjustments.

FIG. 6A displays a gas flow passage 103 aligned with a plasma beam 111.Each plasma beam comprises halo electrons “h”, axial ions “P1”, paraxialions “P2”, and neutrals “N”. During processing, lid 106 is dropped downon the gas distribution plate surface to seal off the other passages.Everything is turned off except an argon supply line that fills theinner compartment of the vacuum discharge chuck. That provides a flow ofargon gas Ar “A” to fill the atmosphere through the plenum, groundedmesh, passage, and inlet.

Ar flows up moving against the plasma beam. These Ar atoms collide withelectrons n, axial ions P1, paraxial ions P2, and neutrals N. Some areionized and enrich the plasma density of the plasma beam. A brighterglow when approaching the inlet tip of the plasma beam occurs that canbe sensed by light detectors and give feedback that the plasma beam hasproperly targeted the passage and they are aligned.

FIG. 6B represents how plasma beams can encounter congestion inside gasdistribution plate passages caused by a Debye sheath layer. Accumulatingelectrons impede deeper penetration. FIG. 6B shows halo electrons “h”,axial ions “P1”, paraxial ions “P2”, and neutrals “N”, just above a gasflow passage inlet.

Continuing plasma beam equilibrium depends on the distribution of thesecharges across a cross-section. Initially, within aerodynamicallyaccelerated plasma beam 111, positive ions P1 and P2 and neutrals N flytight together along the axis. The halo electrons h wrap around in ajacket on the periphery.

Plasma beams 111 trying to enter such millimeter scale gas flow passages103 will suffer undesirable plasma beam degradations caused by adversespace charge effects. Stronger, Coulomb interactions can be expectedwith increases in the plasma density as the focal plane is approached.

Free in the atmosphere, the spatial distribution of potentials in aspace charge are compensated by a negative electron halo formationaround a positive core. These halo electrons are produced by residualgas ionizations and recombination processes inside beam 111, andcompensate the space charges the potentials in the positively chargedplasma beam core.

However, plasma beams 111 moving through narrow gas flow passages 103become impeded by the very halo electron they lose to the inside walls.But the effects cannot be explained just by incomplete neutralization ofthe beam space charge caused by losses of the halo electrons. The plasmabeam 111 gets congested by a collective behavior of three effects,including the space charge, Debye sheath and recombination processes.

As plasma beam 111 loses its halo electrons, the beams diffuse becausethe space charge electrical forces are no longer being compensated. Soions push out from the beam. The plasma beam loses both its negative andpositive species and becomes completely diffused.

The Debye sheath layer is supplied mostly by halo electrons that stuckon the inside walls and builds from pieces of the plasma beam into aplug. The halo electrons continually enlarge the Debye layer down thegas flow passage walls to the outlet. FIG. 6B.

The Debye sheath has a negative potential of around 5 eV. Thepenetrating energy in plasma beam 111 is only around 0.04 eV. The Debyesheath potential will prevail, causing halo electron deflections,recombinations, and beam dissipation. The gas flow passage getscongested and impedes the plasma beam.

Near a sheath boundary, all negative species will be repelled, and allpositive ions which reach that far in will turn into the gas flowpassage wall and away from their original path down the gas flowpassage. However, fast neutrals will soar unimpeded past the Debye layer“Db” and out through the gas flow passage outlet. Although the plasmabeam is not completely stalled, it is demoted into a molecular beam.

The fast neutrals penetrate gas flow passages 103 and make it down intothe vacuum discharge chuck and through copper mesh 202. Depleted streamslike this cannot be used as carriers for etching gases or vaporizednanoparticles.

FIG. 6C shows a method embodiment of the present invention oferadicating Debye layers using an auxiliary CCP discharge 200 speciallygenerated in the vacuum discharge chuck. A low-pressure capacitivelycoupled plasma (COP) discharge in an argon flow directed from plenumgrate 810 (FIG. 8) through copper mesh 202 is powered by an RFgenerator. The discharge pushes near the underside of the GDP workpiece102, and especially at the gas flow passage outlets. There it ionizesatoms of argon that are attracted by the Debye layer's negativepotentials. The ionized argon atoms accelerate up inside each gas flowpassage guided by the plasma beam 111.

The energies these ions gain from the Debye potential is enough to knockout electrons sticking on the outlet walls and produce an ion-electronemission.

The ion-electron emission, the Debye sheath potential, the positive ionsupply from the COP discharge, and the neutrals molecular flow supplycoming through from the inlet all create the conditions needed to launcha hollow discharge inside the gas flow passage. Particularly in thepassage outlet

The hollow discharge neutralizes the Debye layer, starting in theoutlet, and propagates up inside the congested gas flow passages.Eventually, the propagating hollow discharge couples the plasma beamwith the CCP discharge. The gas flow passage then clears itself of thecongestion caused by the Debye layer.

FIG. 6D exemplifies a breaching and weakening of the Debye layer Db bythe plasma beam and the hollow discharge. At, some point in the gas flowpassage, the Debye layer becomes weak enough for the positive ions inthe plasma beam 11 to breach and travel down to the COP discharge andcopper mesh 202. As it propagates down through the gas flow passage,plasma beam. 111 eventually connects through copper mesh 202 and the RFgenerator.

FIG. 6E illustrates a final phase in the penetration when the RFgenerator discharges through the plasma beam up through. the gas flowpassage. A filament-like high conductivity streamer develops that movesup through the plasma beam in the reverse direction.

FIG. 7 represents a twenty nanometer diameter nanoparticle 702 that willbe used to coat the inside walls of a gas flow passage. But beforenanoparticle 702 can be used it has to be pre-melted at 600° C. toreduce the surface forces in a melted shell 704. Then it is liquefied at1200° C. into a melted drop 706 in the upper plasma reactor. The lowerplasma reactor vaporizes it at 2000° C. to produce a nanopowder vapor708 to be carried in with the plasma beams in array 110.

Commercial nanopowders less than twenty nanometers in diameter arerequired to produce good results. Such nanopowders are difficult tovaporize directly in plasma reactors because of their large surfaceareas and specific surface energy. The melting point of nanoparticle ofY₂O₃ can be reduced to less than half in comparison to the bulkmaterial. Pre-melting of the nanoparticles at temperatures of 600° C.helps with their later vaporization in the plasma reactor because thespecific surface energy is disrupted. The vaporization powers necessaryin the plasma reactor can thereby be reduced. This reduces the thermalloads and increases the reactor lifetimes.

The so-called melting point depression (MPD) phenomenon is employed byus here to improve the complete vaporization of nanopowders. Thebeneficial effects of MPD will diminish with any aggregation of thenanoparticles into clusters. The forces that cluster nanoparticlestogether include van der Waals bonds. such bonds can be annihilated byapplying Coulomb forces. Our method of charging the nanopowder clusterswith a negative plasma species using the DBD line 136 electricallyimparts the necessary repulsive forces to each nanoparticle. Thisresults in the levels of cluster de-aggregation required.

MPD melting starts at a crystal's surface. The atoms at the surface areless coordinated than those in the interior. So a surface shell willhave a lower melting temperature than does the bulk material. In caseswhere the surface is a significant part of the volume, as innanoparticles, the melting point will be much lower. Melting normallystarts in the surface shell layer, and propagates inwards to the core.

Moving on now to FIG. 8 and vacuum discharge chuck 104, high current RFplasma filaments must be avoided because they can erode the gas flowpassage walls in GDP workpiece 102. Three controls are available forthis, (1) adjusting the gap between copper mesh 202 and GDP workplace102, (2) limiting the level of RF power applied, and (3) maintaining anoptimum flow rate of argon from plenum 810.

The plasma beam 111 from above in array 110 is boosted from below withadditional heat and an ionized species from auxiliary CCP discharge 200.Together, these keep plasma beam 111 from getting stalled in the Debyesheath congestion. RF plasma filaments are generated that stretch outand reinstate the delivery of etching gases and vaporized nanoparticlesso they can get completely all the way down to reach the gas flowpassage outlets and do their work.

Our etching of the gas flow passages 103 proceeds by pushing in HCl fromboth above and below. We get the HCl etching gases below from the CCPdischarge that ionizes the HCl. An HCl supply injected into vacuumdischarge chuck 104 gets pushed up through plenum 808, grate 810, andcopper mesh 202 up into the COP discharge, and the ionized HCl pushesinto the gas flow passage outlets.

Plenum grate 810 is located just beneath copper mesh 202 by about fivemillimeters. It's completely fenestrated with holes about 0.5 mmm indiameter to provide a uniform distribution of argon flow that willpromote a more even auxiliary CCP discharge 200. Plenum 808 is connectedto an argon supply 806. Copper mesh 202 is electrically connected to anRF generator through a load-matching device.

The manifold is connected through the port 120 to the argon supplyingline and through the port 121 to the HCl supplying line. All theseconnections are managed by mass flow controllers (not shown) set toestablish a low pressure discharge gas mixture inside the innercompartment. A CCP discharge can thereby be simultaneously sustainedwith a vacuum extraction of the spent plasma.

Copper mesh 202 rests on inner glass ring 802 and these can be z-liftedto fine tune the small one millimeter gap above copper mesh 202.Compressed air is fed it to a central coaxial bellows 822. Outer andinner bellow sleeves are welded together to produce a stable non-tiltingplatform. A “bellows cavity” to receive compressed air is enclosedbetween the bellows. At the center is an inner compartment that is usedas a conduit for argon and HCl in plasma discharge 200.

The gap between the bottom surface of the GDP workpiece 102 and coppermesh 202 controls the auxiliary CCP discharge 200 with preciseadjustments by compressed air 824.

An ability to z-adjust copper mesh 202 is needed because copper mesh 202is not very flat, relative to the optimum one millimeter gap. The RFpower applied across the gap must sustain the auxiliary CCP discharge200, but not allow surface sputtering of copper of mesh so near theunderside of GDP workpiece 102. The gap must therefore be adjusted witheach new positioning of GDP workpiece 102.

FIG. 8 shows CCP vacuum discharge chuck 104 of FIG. 1 in more detail.The sealing necessary on the top of vacuum chuck 104 is provided bysealing lid 106. Too much air leakage would occur if lid 106 was notused to cover all the gas flow passages 103 in the gas distributionplate not being exposed. During positioning, lid 106 is lifted up so theCNC system can shift the vacuum discharge chuck for its positioningrelatively to the beam in order to expose for such treatment each gaspassage. The clearance for such movement is controlled by the dropmechanism.

Discharge chuck 104 is principally divided into an inner compartment tobring argon or HCl in as a discharge gas for auxiliary CCP discharge200, and an outer compartment to exhaust out all the spent gases. Thesetwo compartments are respectively defined by inner and outer glass rings802 and 804. These glass rings provide both the gas containment and theelectrical isolation needed between copper mesh 202 and GDP workpiece102 which sit on top of each.

RF power is applied through a load matching device between the coppermesh 202 and the GDP workpiece 102 in a capacitively coupled plasma(CCP) arrangement that generates a positive species auxiliary plasma 200in either of the Ar and HCl discharge gases supplied from below.

The inner compartment receives the discharge gas under pressure pushedup inside a plenum 808 and through a Teflon grate 810. The Teflon grate810 has fenestrations to uniformly distribute the argon and HCl flowsand send them toward and through copper mesh 202. CCP discharge 200clouds just under a portion of the bottom side of GDP workpiece 102 andjust above copper mesh 202 in a small gap of about one millimeter. Suchgap is critical and therefore must be finely tuned.

The spent gases in the outer compartment inside glass ring 804 andoutside glass ring 802 are vacuum exhausted by a vacuum pump through anexhaust port 820.

The optimum one millimeter gap between GDP workpiece 102 and copper mesh202 is made adjustable by a z-lift bellows 822 that is pneumaticallycontrolled by varying the air pressure applied at a compressed air port824. A z-adjustment 826 should move copper mesh 202 up high enough toinitiate positive species auxiliary plasma 200 in the discharge gases,but not so close as to produce arcing and sputtering.

The interior vacuum of chuck 104 is enough to hold GDP workpiece 102firmly in place, while remaining well sealed to outer glass electrodering 804. A CNC x-y positioning table (not shown) is included toproperly position the GDP workpiece 102 so the plasma beam array 110 isalways aligned with a chosen set of gas flow passages 103. Suchalignment can be confirmed with detectors to sense glows in thedischarge gases at the entries of the gas flow passages 103 duringsetup. FIG. 6A.

A lifting/dropping mechanism is included to lift sealing lid 106 up whenthe GDP workpiece 102 is to be repositioned, and lets it drop back downonce the gas flow passage addressing is complete. The GDP workpiece 102typically has over nine hundred gas flow passages 103 and it would bedifficult to maintain the required atmosphere underneath if most ofthese were left uncovered.

FIGS. 9A and 9B represent dielectric barrier discharge line 136 of FIG.1 in more detail. Schematically, in FIG. 9A, several needles 900 withsharp points are each respectively disposed in a narrow blind channel902. An inflow of nanopowders 904 is received from a cloud generator1300 (FIGS. 13A-13C). The needles 900 must operate in an argonatmosphere. Nanopowder cluster aggregates 904 to be de-aggregated flowinto a main glass tube 906 from the left, and then move right pastseveral energized tips of needles 900. Individual nanoparticles 908 inclusters 904 are jolted with a negative charge of electrons from thetips of the needles. Each nanoparticle takes on a negative charge andwill thereafter repel one another. The cluster will disband. Newlyde-aggregated individual nanoparticles 908 flow out of main tube 906 tothe right. The nanoparticles can now take advantage of melting pointdepression effects.

RF power 910 is applied to all the needles 900 in parallel with aninductor 912. The outside of main glass tube 906 has a conductivecoating 914 that is painted on or sputtered on in a metallic film.Conductive coating 914 is grounded. Just inside main glass tube 906 anelectron charge layer 916 will collect to form a virtual capacitor(C_(virtual)) 918. Such combination virtually creates an RLC generator920 that operates in resonance to produce large voltages on the needles900 without requiring large amounts of RF power 910.

Nanopowder is injected after being extracted from its package with apuncher 1202 (FIGS. 2 and 14). The cloud generator accumulates a portionof the powder into a vibrator, stirs it with an interior propeller, andshakes it with a rocking-wave generator to produce a nanopowder cloud1302. A turbo-pump 1214 sucks up nanopowder cloud 1302 and pushes it tothe dielectric barrier discharge line 136 for de-aggregation.

If dielectric barrier discharge line 136 was conventionally constructed,too many nanopowders would collect on the tips of needles 900 and foulthem. So individual flows 922 of argon gas is inserted into the middleof each narrow blind channel 902 from a distribution manifold 924. Thiscauses a distal argon wind to stream off the tips of needles 900 suchthat the nanopowders cannot attach and stick easily.

Dielectric barrier discharge (DBD) line embodiments of the presentinvention are quite novel. Conventional DBD lines proved to beinadequate and unsatisfactory in these applications. Conventional DBD'srequire a high RF power to initiate, and this can cause the discharge tobe overheated.

Our DBD line 136 is novel in that it is powered by a RF current thatflows into inductor 912, not just needles 900. The inductor accumulatesenergy in its magnetic field that creates high voltage peaks between theelectrodes as it resonates. The needles' sharp points form a fieldemission triple-point in an electric field that readily ejectselectrons.

During each negative voltage half-cycle of the alternating RF power 910,the needles each send out steamers of electrons to pass through the flowof argon on their way to ground, e.g., the conductive paint. Thedielectric material of the glass walls stops the electrons and causesthem to film inside the glass wall. Mirrored dipoles develop in thegrounded conductive paint layer on the wall just outside.

These dipoles keep the electron film in place on the inside surface. Theelectrons accumulate after many cycles to build a large charge and highaccumulated voltage.

On positive voltage half-cycles of the alternating RF power 910, theaccumulated electrons leave the glass surface inside and fly back towardthe needles in a now positive electric field. The voltages accumulatedare so strong the currents produced are able to breakdown the argon.

A virtual capacitor C_(virtual) develops between the conductive groundedlayer on the outside wall and the piled up electron layer deposited onthe inside surface. The glass acts as the dielectric of this capacitor.This virtual capacitor C_(virtual) and a properly chosen inductor wiredin parallel are operated in resonance, e.g., at 13.56 MHz.

The resonance will sustain a DBD discharge at a relatively low RF powerinput investment, because accumulated energy is stored in the virtualcapacitor and in the inductor. At resonance, the parallel circuitimpedance reaches to maximum and the voltage swings across the inductorcan reach very large maximums.

The inclusion of an inductor in parallel with the DBD load is novel andenables operation with only very low RF power levels.

Straight flows of Y₂O₃ nanoparticles at right angles past the needles900 can lead to fouling with ceramic deposits and those will seriouslydegrade the DBD's performance. So, an auxiliary flow of argon is plumbedin to enter behind each needle's tip. A shield gas then flows around thedischarging tips to keep the nanoparticles away. These tips can generatetheir local discharges free of the risks of fouling by not beingimmersed in nanopowder.

FIG. 10 represents a method 1000 for extending the service life and forrefurbishing worn/damaged aluminum gas distribution plates using theAP-ICP treatment system like that illustrated in FIGS. 1-9. The sequencesteps of method 1000 are preferably automated with a microcontroller,but here we describe the constituent manual steps.

In the case of refurbishing gas distribution plates made of billetaluminum, there will be chemical reaction byproducts of AlF₃ left behindin its prior life that must be washed away. Plasma beams formed fromatomic hydrogen are used to do this as well.

There are five basic sub-goals that are to be accomplished by method1000: 1) The inside walls of the gas flow passages 103 must be cleanedof contaminants of prior-life PE-CVD process with plasma beams formedfrom hydrogen chloride gas (HCl), 2) The chemical reaction byproductsleft behind by such HCl plasma cleaning must be rinsed away with plasmabeams formed from atomic hydrogen, 3) The surfaces of the passage wallsmust be pre-heated with plasma beams formed from argon gas to betteradhere a nanocoating of Yttrium oxide nanopowders in a Y₂O₃ vapor, 4)The surfaces of the passage walls must be exposed to a Y₂O₃ vaporcarried in by plasma beams formed from argon gas to improve the gasdistribution plates with plasma-chemical corrosion protection, and, 5)the deposited layers of Y₂O₃ nanopowders must be annealed by heatingfrom plasma beams formed from argon gas so they better adhere to thesurfaces of the walls of the passages.

Method 1000 starts by lifting up sealing lid 106 and loading in a nextGDP workpiece 102 into the top of vacuum discharge chuck 104. A step1002 x-y positions the gas distribution plate with a CNC-stage and dropsthe sealing lid 106 back down. The CCP auxiliary CCP discharge 200 underthe gas flow distribution plate 102 is lit and operational.

Refurbishment processing begins with a two-step etching. A step 1004cleans the inside walls of the gas flow passages 103 of contaminantswith plasma beams 111 formed from hydrogen chloride gas (HCl). A step1006 changes the discharge gases selected for inflow at the Teflon topflange 130 to hydrogen chloride gas (HCl).

A step 1008 rinses away the chemical reaction byproducts left behind bysuch HCl plasma cleaning with plasma beams formed from atomic hydrogen.A step 1010 changes the discharge gases selected for inflow at theTeflon top flange 130 to atomic hydrogen (H) that has been disassociatedby the dielectric barrier discharge line 136 from molecular hydrogen gas(H2).

A dense enough nanocoating in gas flow passages 103 requires that theY₂O₃ nanoparticles to be completely vaporized after the inside surfacesare pre-heated to 550° C. The layer of Y₂O₃ deposited will have anamorphous microstructure as a result of nuclei-less ballisticdeposition. Finishing with a fusion step anneals the new surface of theY₂O₃ amorphous layer for better adhesion.

A step 1012 pre-heats the surfaces of the passage walls with plasmabeams 111 formed from argon gas. A step 1014 changes the discharge gasesselected for inflow at the Teflon top flange 130 to argon gas (Ar).

A step 1016 exposes the surfaces of the passage walls to a Y₂O₃ vaporcarried in by plasma beams 111 formed from argon gas. A step 1018changes the discharge gases selected for inflow at the Teflon top flange130 to argon gas (Ar). Pre-melted Yttrium oxide nanopowders in a Y₂O₃vapor are supplied by dielectric barrier discharge line 136. Severalmass flow controllers 134 are configured in parallel to distribute auniform coating via each plasma beam 111.

A step 1020 anneals the deposited layers of Y₂O₃ nanopowders by heatingwith plasma beams formed from argon gas. A step 1022 changes thedischarge gases selected for inflow at the Teflon top flange 130 toargon gas (Ar).

A step 1024 asks if the last set of gas flow passages 103 has beentreated. If not, step 1002 is repeated. A step 1026 releases the vacuumseal on the gas flow distribution plate for removal.

FIG. 11 represents a way of addressing and aligning the nine hundred orso gas flow passages 103 in a typical GDP workpiece 102 that are set inradial groups. Eight gas flow passages 103 at a time are brought underthe multi-beam plasma array (e.g., AP-ICP torches of FIGS. 1, 2, 3,4A-4C, and 5). In one embodiment, the torches are fixed above GDPworkpiece 102 and can move only vertically. It is GDP workpiece 102 thatis rotated and x-y positioned beneath.

Given eight plasma beams in array 110, and nine hundred gas flowpassages 103 in GDP workpiece 102, the GDP workpiece 102 would need tobe repositioned at least one hundred and thirteen times to complete therefurbishment of one GDP workpiece 102. It is assumed here theinter-beam spacing between plasma beams in array 110 matches some wholemultiple of the radial and inline spacing of the gas flow passages 103in GDP workpiece 102.

FIG. 12 illustrates a three-stage, batch delivery, nanopowder cloudsupply sub-system 1200. In a first stage, a package puncher 1202accesses a nanopowder in a package 1204 and an argon puff 1206 blows thenanopowder in through a three-way valve 1208. Then in a second stage, ananopowder cloud generator 1212 spins up and whips the nanopowder into acloud by spinning its impeller vanes. Lastly, when ready, a third stageswitches three-way valve 1208 to receive an argon push 1210 that assistsa turbo-pump 1214 to suction out the nanopowder cloud and deliver it inone batch to a dielectric barrier discharge line 1216 for de-aggregationof its nanoparticle clusters.

The nanopowder cloud generator 1212 requires constant agitation,vibration, and rocker-shaking, e.g., to minimize the aggregation ofnanoparticles that tend to collect on the inside walls. Its impeller isspun at 360 rev/min, the whole assembly is vibrated at one kilohertz,and a rocker-shaker device cycles at 3-4 times a second.

The three-stage nanopowder cloud generation operates in batches, itcannot supply materials in a constant stream. So the third stageoperation has to be synchronized to occur at those times when the gasflow passages 103 in the gas distributing plate 102 have been readied toreceive the nanopowder vapors.

The delivery of prepared nanopowders in clouds and the overall flowrates possible is limited by a number of the devices involved. Theturbo-pump has a very limited suction rate, the de-aggregator cannotwork effectively at high feeding rates, the top plasma torch also cannotpre-melt high flows of nanopowder, and the bottom torch cannot vaporizelarge amounts of nanopowder. The plasma beam nozzle orifices can getclogged if too much nanopowder vapor is pushed, and the plasma beampenetration will be doused. Bottom-line, good adhesion quality duringdeposition can only be pushed so much because the pre-heated surface ofthe inside walls of the passages cannot accept a lot of vapor if it isto fuse well into the metal. So good nanopowder delivery and depositioncan be tedious and challenging to control.

FIGS. 13A-13C illustrate a nanopowder cloud generator 1300 that could beused as the nanopowder cloud generator 1212 in FIG. 12. Nanopowder cloudgenerator 1300 is generally constructed of glass so an operator canvisually confirm the presence and status of a nanopowder cloud 1302inside.

FIG. 13C shows the nanopowder cloud generator in a “normal” verticallystanding orientation in which the impeller shaft 1310 is at the top anda nanopowder well 1313 is down at the bottom. A rocker-shaker, heater,and vibrator (not shown) tilt the bottom up in a rocking motion 3-4times a second, while vibrating at one kilohertz, and heating to keepnanoparticles from clumping or sticking on the inside surfaces. Theheating also drives out moisture and prevents water condensation.

Nanoparticles in an argon gas carrier from package puncher 1202initially enter intake 1316 and into a sleeve compartment 1307 inbetween the inner glass electrode 1306 and an outer glass electrode1312. Each new nanopowder cloud 1302 is whipped up in a batch by spiraltwisted impeller vanes 1304. These lift the nanoparticles up and spinthem in a vortex 1305 within an inner glass electrode 1306.

Intakes 1316 and 1318 and their connection to compartment 1307, as seenin FIG. 13C, essentially constitute the three-way valve 1208 of FIG. 12.

The production of each new nanopowder cloud 1302 may take some time, butwhen it's ready, an argon gas pusher is applied to intake 1318 to helpturbo-pump 1214 pull it out exhaust port 1320. The timing of each newbatch of nanopowder cloud 1302 is controlled by synchronization signal1220.

The cloud exhaust 1320 in the throat 1314 serves to withdraw thenanopowder cloud to the turbo-pump. A top portion of the throat abovehole serves also as a bushing nest for impeller 1310. The bushing ringis made of Teflon. Nanopowder carried in with argon from the puncherenters through the wall in outer electrode 1312 into compartment 1307between the inner and outer electrodes of glass. The inner electrode1306 stops short, where nanopowder is dropped in the bottom well 1313.

Spiral twisted impeller vanes 1304 break up the nanopowder flow and donot allow it to drop back into the bottom. The nanopowder flow spins upin a rotating vortex 1305, and eventually up to and into throat 1314.During this tornado-like cloud generation period, a valve from puncher1202 must be closed so no more nanopowder can come in or be blown back.

The time required to be off-line depends on the impeller revolutions,frequency of the rocking wave generator, and vibrations applied. Thistime off is used productively to x-y step the gas distribution plateunder the array 110 from one corresponding array of gas flow passages103 to another. The plasma beams 111 are left running, but no nanopowderis injected into them.

When the plasma beams are exposed to a next new array of gas flowpassages 103, a valve opens to a puffing argon 1210 that assists therather weak turbo-pump 1214 to exhaust the nanopowder cloud out from thecloud generator.

The cloud generator has a housing that is double-walled and surroundscoaxially rotating impeller vanes. The Y₂O₃ nanopowder in argon isreceived into the spaces between the walls from the bottom. The impellervanes 1304 further disperse the nanopowder in the carrier argon.Constant rocker-shaking is needed because the clouds generated wouldotherwise just lay in the bottom. The changing positions lift the bottomup and slosh the cloud 1302 around.

The strong vibrations applied also help keep particles from the cloud1302 from accumulating on the inside walls. The high speed vanes 1304help break apart large clumps and mechanically separate the smallerclusters for better de-aggregation in the dielectric barrier dischargeline 136.

FIG. 14 shows a nanopowder package puncher 1400 in more detail than inFIG. 12. A top flange 1402 has four punch heads 1404 like twist bitdrills that each retract into a silo nest 1406. Each punch head 1404 hasa punch stem 1407.

Four packages of nanopowder 1408 can be loaded two-by-two on a mesh 1410in a middle flange 1412. Each lays against its own punch head 1404 in acompartment between the top and the middle flange. This compartment isfilled with argon gas. Each package is good for one-day of work only,because nanopowder powder is perishable. So just one rotating punch israised from the silo nest to rupture a fresh package. The nanopowderdrops down through the mesh onto a flexible membrane 1414. Membrane 1414is vibrated by pulsed argon gas supplied through a nipple 1416. Thenanopowder is then inhaled with the argon puffed into the puncher backthrough nipple 1416 and into cloud generator 1300.

Nanopowder is very expensive and has a short lifetime even if stored inargon. This simple system 1400 helps extend the storage life as best ascan be done once the package is opened.

The remaining FIGS. 15A-15E and 16 are related to the refurbishment ofsilicon gas distribution plates that require restoration of siliconmaterial lost in exposure of the gas flow exits to process etchants.

In summary of our aluminum gas plate refurbishment, three complexphysical models are important: 1) our novel dielectric barrierdischarge, 2) our novel way of extracting and focusing the plasma beams111 from nozzles congested with Debye electrons, and 3) our novelmethods to get plasma beams to penetrate narrow gas flow passages 103also congested with Debye electrons.

With regard to our novel dielectric barrier discharge illustrated inFIGS. 9A and 9B, needles 900 eject electrons during each negative peakof the RF half-wave. But such electrons cannot get to ground in thegrounded conductive paint because they cannot penetrate the dielectricbarrier glass. If the electrons were left to simply deposit on the innerglass surface, they would quickly spread all over the total glasssurface and be lost to any useful purpose.

A force is needed to sustain the free electrons in place proximate thetips of the needles. A mirrored positive charge can be positionedagainst each electron by grounding a smooth, highly conductive paint, ora magnetron-sputtered aluminum film just outside on the glass barrier.The glass wall should be thin, about a half of a millimeter (0.5 mm)thick.

The electrons and their mirrored positive charges create strong dipolesthat, in own turn, create strong sticking forces that will accumulatethe electrons over extended periods. A virtual capacitor exists thenbetween the layer of electrons and the conductive outside layer.

Large electron charges flow onto the needles during the positivehalf-wave peaks of the applied RF power. The electrons accumulatedinside the glass fly off the inner surfaces and accelerate in theelectric fields created. These break down only the clean argon that camefrom the ports on the sides above the needle tips, not the argon flowclouded with nanoparticles.

The accumulated energy in the coil produces very large voltage peaks onthe tips of the needles. An independent circuit is thus formed throughthe coil, the tips of the needles, the virtual capacitor, ground andback to the coil again. Such circuit is a relaxation R LC generator. Lis inductance of the coil, C—capacitance of the virtual capacitor, R—thebreakdown resistance of the plasma discharge. The generator has its ownresonant frequency

$f = {\frac{1}{LC}.}$

The Rf generator has only to power a small coil. This is what isdifferent from conventional devices that apply huge RF power straightfrom a matching network to the needles without any inductive loading orresonance.

Many of the components and concepts described and discussed above areapplicable to our system and method for refurbishing silicon gasdistribution plates as marketed by Tokyo Electron Ltd (TEL), LamResearch, and others.

FIGS. 15A-15E illustrate the use of our modified Bosch Process to repairthe outlets of gas flow passages in silicon gas distribution plates1638. The conventional Bosch Process applies a passivation layer inrepeated steps interdigitated with anisotropic etching steps.Embodiments of the present invention deposit silicon from vapors insteadof the passivation layer. Our solutions to the Debye congestions in thenozzles 112 and gas flow passages 103 that impede plasma beams 111 applyhere as well.

FIGS. 15A-15C represent a three-step cycle for: (1) silicon deposition,(2) anisotropic etching that follows crystal planes, and (3)annealing/bonding. FIG. 15D represents how a sliding movement of thesilicon gas distribution plate is accommodated to treat a next gas flowpassage 1636. FIG. 15E represents how an argon glow 1634 at the outletsof gas flow passages 1636 in silicon gas distribution plates(showerheads) 1638 under the plasma beam 1624 can be used as a visualindicator of proper alignment. Each gas flow passage outlet 1636 has atypical cavity depth of 1.0-1.2 mm.

Silicon-type gas distribution plates 1638 are actually slices of asingle crystal of silicon cut along its lattice plane. Anisotropicetching can therefore be used to etch deep cavities along crystal planeswith near perfect vertical walls.

FIG. 15A represents gas flow passage 1636 (FIG. 16) during a first stepof silicon (Si) deposition 1500 in the three-step cycle. A plasma beam1624, is directed into an eroded outlet 1636 that suffered losses ofsilicon and needs to be repaired. An insulated bias lid 1502 and 1504,here 1628, is dropped down and its conductive top side serves as a RFbias electrode 1630. Argon gas 1510 is injected into discharge chuck 104through plenum 810 and on to flow through mesh 202. A bottom auxiliaryCCP discharge 200 is launched by applying RF power, and a top biasdischarge 1506 is launched by applying a bias voltage to bias lid 1502.

Silicon nanoparticles 1602 are injected after de-aggregation into a topplasma discharge of a beam generation system 1600 like that of FIG. 16.These silicon nanoparticles are vaporized in a bottom plasma dischargeof the beam generation system. A resulting silicon vapor flow isaccelerated toward eroded gas passage outlet 1636.

Embodiments of the present invention suddenly reduce the velocity ofsupersonic silicon vapor flow proximate to where the silicon should bedeposited by generating bias discharge 1634 in eroded passage outlets1636. The top biased discharge 1506, 1634 slows down the vapor flow anddiffuses it for better adhesion with the damaged walls. A superiorquality silicon layer can thus be deposited on the sidewalls of theeroded cavity of gas flow passage.

FIG. 15B, represents what happens in gas flow passage 1636 during asecond step of etching 1520 in the three-step cycle. The silicondelivery of step 1500 is turned off, as is the bias discharge 1634.Sulfur hexafluoride (SF₆) is injected into the top plasma discharge. Ahot SF₆ vapor flow is created and then accelerated toward the gas flowpassage outlet. Any weak aggregations of silicon that built-up in theoutlet are knocked off and flushed. The inside walls of the gas flowpassage are purged of loose particles to prevent interference later withsilicon deposition.

FIG. 15C, represents gas flow passage 1636 during a third step ofetching 1530 in the three-step cycle. A mixture of argon-hydrogen gas isinjected into the plasma discharge as discharge gas 1608. This resultsin a mixed, high temperature argon-hydrogen plasma beam 1624 beingoutput and directed toward outlet 1636. The inside walls of gas flowpassage 1636 are heated enough to bond any deposited silicon layer intothe crystalline structure of the silicon substrate of the gasdistribution plate. Thereafter, the inside walls are purged of anyremaining byproducts of the SF₆ etching.

One hundred of these three-cycle steps will typically be needed torestore the gas passages that were eroded in the showerhead.

FIG. 16 represents a plasma beam generation and bias discharge apparatus1600 in an embodiment of the present invention for refurbishing wornsilicon showerheads. Typical silicon showerheads suffer the most erosionto the gas flow passage outlets out on the periphery on the processface. These passage outlets can become so damaged that the siliconshowerhead must be taken out of service even though the majority of gasflow passage outlets around the middle are alright. So when thesesilicon showerheads are refurbished, only those gas flow passage outletsout on the periphery will typically need any restoration treatment.

The complete plasma beam generation and bias discharge apparatus 1600 issimilar in many ways to corresponding components described with FIG. 1.The plasma torch is basically the same AP-ICP two stage device withupper and lower reactors each with respective pairs of RF powerantennas. The complete plasma beam generation and bias dischargeapparatus 1600 produces, however, only one plasma beam 1624.

A source of nanoparticles 1602 enters at top from a nanopowder cloudgenerator, as in FIGS. 13A-13C, and must be de-aggregated as was doneabove with the dielectric barrier discharge line 136 of FIGS. 9A and 9B.Such nanoparticles 1602 are injected through by cylindrical centralglass tube 1604. This is enveloped by an intermediate glass tube 1606that enables an injection of a plasma discharge gas 1608.

A top plasma reactor includes a cylindrical top confinement tube 1610 toreceive the nanoparticles and discharge gas. A top saddle RF antenna1612 wraps closely around top confinement tube 1610. It is driven by RFpower from load-matching networks, top saddle RF antenna 1612 is finetuned to reduce reflecting waves.

A top sheath gas 1614 is inserted through fine manifolds to surround theplasma produced inside the top plasma reactor. Thin jackets of inert gaslike this protect the inside glass walls from the plasma.

A bottom plasma reactor includes a larger cylindrical bottom confinementtube 1616. This receives the plasma and any pre-melted nanoparticlesfrom the top reactor. A bottom saddle RF antenna 1618 is wrapped closelyaround bottom confinement tube 1616. It is driven by a different sourceof RF power than the top to reduce cross coupling. This second RF sourcehas its own load-matching networks, and it too is fine tuned to reducereflecting waves. A bottom sheath gas 1620 is also inserted through finemanifolds connecting the top and bottom confinement tubes. Suchsurrounds the hotter bottom plasma produced inside the bottom plasmareactor in a thin jacket of inert gas that continues the protection ofthe glass walls.

A conical glass nozzle 1622 brings the plasma flow inside down to amillimeter scale point to produce an aerodynamic supersonic plasma beam1624. Such is the equivalent of plasma beams 111 described above. Plasmabeam 1624 is variably focused by an extractor 1626 to bring the plasmabeam's focal plane coincident with various points inside the gas flowpassages.

Extractor 1626 also functions to decongest the Debye sheathing buildupof electrons inside the tip of conical glass nozzle 1622.

A bias lid 1628 is similar to sealing lid 106, but has an importantadded function. Bias lid 1628 comprises two parts, a conductive RFelectrode 1630 in a top layer electrically connected to receive an RFbias, and an insulative ceramic undercoating 1632 to electricallyisolate the conductive RF electrode 1630. The bias lid 1628 is lifted upand down at various times by a simple mechanism not shown to accommodatemovement of the silicon showerhead 1638.

A bias discharge 1634 can appear to glow at the top facing outlet 1636of eroded gas flow passages when in alignment with plasma beam 1624. Asilicon gas distribution plate 1638 is typical of those manufactured byTEL and Lam Research.

In summary, a principal advantage of the AP-ICP reactor embodiments ofthe present invention is their flexibility in being able to vary coatingarchitectures and processing conditions by focusing of plasma beams 111and 1624. Our AP-ICP focused beam system 1600 is like a 3D-printer inits ability to penetrate narrow and deep hollows like the passages inwafer etching showerheads. Dense coatings can be simultaneouslydeposited in plasma spray-physical vapor deposition (PS-PVD) of ceramicsfor protective coatings of columnar microstructures. These can besuperior to splat-like coatings applied by atmospheric plasma spraying(APS).

B. J. Harder and D. Zhu, of the NASA Glenn Research Center, Cleveland,Ohio, wrote a Paper tiled, PLASMA SPRAY-PHYSICAL VAPOR DEPOSITION(PS-PVD) OF CERAMICS FOR PROTECTIVE COATINGS. They concluded that inorder to generate advanced multilayer thermal and environmentalprotection systems, a new deposition process is needed to bridge the gapbetween conventional plasma spray, which produces relatively thickcoatings on the order of 125-250 microns, and conventional vapor phaseprocesses such as electron beam physical vapor deposition (EB-PVD) whichare limited by relatively slow deposition rates, high investment costs,and coating material vapor pressure requirements. The use of PlasmaSpray-Physical Vapor Deposition (PS-PVD) processing fills this gap andallows thin (<10 μm) single layers to be deposited and multilayercoatings of less than 100 μm to be generated with the flexibility totailor microstructures by changing processing conditions. Coatings ofyttria-stabilized zirconia (YSZ) were applied to NiCrAlY bond coatedsuper alloy substrates using the PS-PVD coater at NASA Glenn ResearchCenter. A design-of-experiments was used to examine the effects ofprocess variables (Ar/He plasma gas ratio, the total plasma gas flow,and the torch current) on chamber pressure and torch power. Coatingthickness, phase and microstructure were evaluated for each set ofdeposition conditions. Low chamber pressures and high power were shownto increase coating thickness and create columnar-like structures.Likewise, high chamber pressures and low power had lower growth rates,but resulted in flatter, more homogeneous layers.

The extensive range of possible microstructures and fast depositionrates make our technology attractive in a wide range of applications,including wear resistant and electrically resistant coatings, diffusionbarrier layers, ion-transport layers for fuel cell components, and gassensing membranes.

In spite of the distinctive differences between AP-ICP and traditionalplasma spraying, they both suffer from effects related to supersonicflows, e.g., ballistic deposition (BD). A ballistic aggregationmechanism grows structure via linear (ballistic) trajectories. BDparticles drop in vertically random positions on an initially flatsubstrate and stick upon first contact. The antistrophic particleaggregation BD belongs to the so-called far-from equilibrium growthprocesses. Here, “far from equilibrium” means that particles are notallowed a relaxation to lowest energy states during the whole growthprocess.

A roughening happens in a way which is different from ordinary diffusionprocesses. Instead of ordinary diffusion process, a nucleation andnano-crystallization occur due to a sticking formation mechanism, theso-called kinetic interface roughening process. The influence ofanisotropy interaction leads to a morphology of growing clusters formedby sticking particles that is characterized by high porosity andpermeability.

A ballistic aggregation model suggests particles are added to a growingstructure by linear (ballistic) trajectories. Other simple modelsinclude diffusion limited aggregation (DLA) and diffusion limitedcluster-cluster aggregation (CCA). These can result in large scallopedand roughen sidewalls. The rough sidewalls cause problems withnon-uniformity in the plasma etching of the wafers. CCA deposits arealso a source of particle contamination in plasma processes.

Particulate contamination is exacerbated by any thermal cycling of thereactor components during repeated plasma processing cycles. Repeatedheating and cooling of the plasma exposed surfaces of showerhead cancause the adhered silicon deposits to exfoliate or flake off due to CTEdifferentials between the silicon buildup and the silicon surfaces ofthe outlets. These silicon deposits can also become dislodged underbombardment by reactant species in the plasma.

Conventional methods could not control turning a kinetic interfaceroughening process from CCA to DLA. 3D-printers using AP-ICP focusedbeams might seem to be able to refurbish gas flow passages in TELshowerheads. But 3D-printer techniques suffer from porosity andpermeability problems in the added silicon. They further suffer frommismatches in the buildup geometry, congestion of the rest of the gashole, and exfoliation under thermal cycling.

Successful TEL silicon showerhead refurbishment requires a completelydifferent process than we use herein for Applied Materials type aluminumgas distribution plates or the showerheads. Refurbishing of the passagesof the Applied aluminum gas distribution plates is essentially a processof etching to remove contaminates, and depositing Y₂O₃ coatings on thegas flow passages walls for plasma corrosion protection.

Refurbishing eroded plasma etching process TEL-type silicon gasdistribution plates or the showerheads requires an additive technologywherein the eroded cavities of the outlets of the gas flow passages arebackfilled with vaporized silicon nanoparticles. These are deliveredwith a focused plasma beam and crystallize on the surface in thecavities. High temperature annealing is then delivered by the same beamduring thermal cycling to fuse it.

The repetitive process adds silicon to the eroded outlets, and isfollowed by a repetitive removal of any extra material that penetratedtoo deep. The vertical structures in the original geometry are restored.Weakly disorganized aggregates that can cause porous cavity formationsare flushed out. As such, our process resembles a modification of theso-called Borsch Process.

The Bosch Process is a high-aspect ratio plasma etching technique thatcycles isotropic etching and fluorocarbon-based protection filmdeposition with quick gas switching. A SF₆ plasma cycle etches silicon,and a C₄F₈ plasma cycle creates a protection layer. The protection filmshave to be thick enough to withstand the highly anisotropic siliconetching in the SF₆ plasma cycle.

The conventional Bosch Process uses pulsed or time-multiplexed etching,it alternates repeatedly between two steps to rebuild (albeit not insilicon) what can be nearly vertical walls:

1. Etching is standard, nearly isotropic plasma based. The plasmaincludes ions that will attack the target wafer primarily vertically.Sulfur hexafluoride [SF₆] is commonly used for such silicon etching.

2. Depositing a chemically inert passivation layer. For instance, a C₄F₈(Octafluorocyclobutane) source gas yields a passivation substancesimilar to Teflon.

Passivation layers are generally used to protect an entire substratefrom supplemental chemical attacks and to stop excessive etching.However, during normal etching, directional ions that bombard thesubstrate can also carry the attack to the passivation layer down alongtrench bottoms. The sidewalls usually miss out. Directional ions collidewith the passivation substance and sputter it off, exposing the baresubstrate for chemical etching.

These small etch/deposit steps are repeated in then conventional BoschProcess many times to result in a large degree of isotropic etch takingplace only at the bottom of the trenches and pits. Etching through a 0.5mm silicon wafer, for example, would require 100-1000 small etch/depositsteps. The two-phase process can cause the vertical sidewalls tohorizontally undulate with an amplitude of about 100-500 nm. The cycletimes can be adjusted to control this effect. Short cycles are used toproduce smoother walls, and longer cycles realize higher rates ofetching.

These etch/deposit steps are widely used for chemical drilling of deepholes in silicon wafers and to mill various MEMS and through silicon via(TSV) technology nanostructures.

We have replaced the passivation process used in the Bosch techniquewith a our unique silicon deposition process in embodiments of thepresent invention. This is made possible by the focused AP-ICP plasmatorch embodiments of the present invention and our novel top biasdischarge. Bias lid 1628 is a key part, due to the electric fieldeffects RF bias electrode 1630 has on the discharge below.

In one aspect, embodiments of the present invention include an AP-ICPplasma beam generation system connected to a silicon nanopowder deliverysystem, an extractor, an isolation lid with a lid-dropping mechanism,and a discharge chuck that holds a silicon showerhead. An auxiliary CCPdischarge generating mesh is connected to receive a discharge gassupply. It is associated with a bias discharge generator and plasmacoupling. A bias discharge 1634 discharge is ignited between the erodedside of the showerhead and the isolation lid. A ballistic deposition ofsilicon is directed to surface of the eroded outlets of the gas flowpassages of the silicon showerhead.

In another aspect, embodiments of the present invention include anAP-ICP plasma beam generation system with a SF₆ delivery system, anextractor, an isolated lid and lid-dropping mechanism, and a dischargechuck holding a silicon showerhead. A ballistic deposition on thesurface of the eroded outlets of the gas flow passages of the showerheadis converted into a nuclei-generation cloud deposition. A bias discharge1634 discharge fills the eroded cavities in the barrel-shaped gas holes.Ballistic supersonic AP-ICP plasma beam flows carrying the silicon vaporenter this bias discharge and are decelerated. The silicon vapor spreadsinside the eroded cavities, and the slowed-down vapors deposit on thesidewalls. Such process includes the nucleation of silicon layers on thesilicon cavity surface, layer by layer in a thick coating of silicon.

In another aspect, embodiments of the present invention include a AP-ICPplasma beam generation system connected to an argon supply and generatean argon plasma beam. It further includes an extractor, an insulated lidwith lid-dropping mechanism, and a discharge chuck to hold a siliconshowerhead. The discharge chuck comprises an auxiliary CCP dischargemesh connected to a discharge gas supply. Penetrating, supersonic AP-ICPplasma beams carry SF₆ into the gas flow passages. The inside walls witha silicon buildup left during silicon deposition are cleaned by removingany weakly organized aggregates that could later exfoliate.

In another aspect, embodiments of the present invention include a AP-ICPplasma beam generation system connected to an argon-hydrogen gas supplyto produce high temperature argon-hydrogen plasma beams. These tooinclude an extractor, an isolated lid with a lid-dropping mechanism, anda discharge chuck to hold a silicon showerhead. This is used forannealing the deposited silicon now filling in the eroded cavities, andheated to crystallization and coalescence with the silicon substrate.

In other words, the conventional multi-cycle Bosch method is modifiedhere to reconstruct the straight-hole geometry of gas flow passages withwell formed bits of silicon. Our modification manifests as a newapplication of focused AP-ICP plasma beams combined with a biasdischarge as a deceleration device to assist silicon depositionnucleation.

Silicon vapors carried by the AP-ICP plasma beam arrive too fast fordeposition nucleation the barrel shaped areas of damaged and erodedcavities in the gas flow passage outlets. The supersonic silicon vaporstream must be slowed down, and we do that herein with the top biasdischarge 1634 discharge.

When the silicon vapor carrying plasma beam 1624 collides with the biasdischarge 1634, a cloud of vaporized silicon droplets results. Thevaporized silicon droplets uniformly disperse inside the cavity in adeposition nucleation on the sidewalls. The bias discharge is sustainedby a RF power applied to lid 1628 and electrode 1630. The opposite endof each gas flow passage 1636 receives an upward flow of ionized argonfrom a bottom auxiliary CCP discharge 200 that coupled with the biasdischarge.

A straight-hole geometry reconstruction of the gas flow passages resultsfrom SF₆ gas etching carried in by the same plasma beam that removesdebris in the center as well as on the inside walls. The rest of the gasflow passage is drained of loose etched silicon with a passivation gasflow from the supply via the cavity to the drain to keep the etch zonesand deposition zones spatially divided.

The third cycle, annealing, uses the same focused AP-ICP plasma beam tocarry a high temperature mixture of argon and hydrogen to bond each newlayer of the silicon nanocoating to the barrel shaped gas hole erosioncavity and to the silicon substrate and the previous layer.

The delivery of ionized etching reactants to clean high aspect holes andthen deliver vaporized Y₂O₃ nanoparticles into those holes is onlypossible if the plasma beam doing the work has a diameter less than thediameter of the hole.

Embodiments of the present invention depend on the unique property ofnanoparticles to be melted and vaporized at the temperatures less thanhalf that for bulk materials. But, that property can only be realized ifnanoparticles less than twenty nanometers can be commercially obtained.

Herein we use a two-step thermal treatment of these nanoparticles, e.g.,where the first step is to activate the surface energy by melting thenanoparticle shells. Then the liquidated surfaces will squeeze theinternal energy. However, complete liquidation and vaporization of thecore requires outside thermal energy.

Nanopowder-based coating systems should be equipped to deliverde-aggregated nanoparticles into the plasma, and then apply apre-melting plasma reactor and a vaporizing reactor.

The refurbishing of showerheads includes: (1) chemical etching of thehigh aspect millimeter scale passages with hydrogen chloride gas toremove products of PECVD processing like organic contaminants; (2)Chemical etching by the ionized hydrogen for removing the product ofplasma chemical reaction in PVD process like AlF3; (3) Deposition ofvaporized Y2O3 on the inner wall of the passages; (4) Hydrogen annealingthe amorphous Y₂O₃ to increase adhesion to the aluminum wall andcohesion inside the coating.

So, FIG. 17 represents a refurbishing system 1700 that includes twodistinct and specialized AP-ICP system parts. The first is a one-stageetching and annealing system part 1710 to support hydrogen chlorine andhydrogen gas delivery. The generation of atmospheric pressure hydrogenplasma requires high levels of RF power to dissociate molecularhydrogen. So, a de-aggregator is included to dissociate molecularhydrogen into atomic hydrogen before it is ICP-heated into a hydrogenplasma beam 1712.

The second distinct and specialized AP-ICP system part is a two-stageplasma system part 1720 for Y₂O₃ nanoparticle deposition, and thatoutputs a nanoparticle vapor plasma beam 1722.

A vacuum chuck 1730 is shared by both of the distinct and specializedAP-ICP system parts 1710 and 1720 to hold and position the sampleworkpiece, e.g., an aluminum showerhead 1740. Vacuum chuck 1730 shareslid dropping subsystems 1731-1733 and 1736-1739. An auxiliary CCPdischarge 1741-1744 is included with discharge chuck 1745.

A gas delivery system sends a mix of argon and 5% hydrogen chlorine forinjection into the discharge chuck for double-sided etching of organiccontaminants when cleaning the passages of aluminum gas distributionplates.

The deposition part 1720 functionally includes: (1) a nano-delivery unit1751-1754 (2) a nanoparticle de-aggregator 1755, (3) a nanoparticlepre-heater 1756, (4) an AP-ICP nanoparticle pre-melting stage 1757-1761,(5) an AP-ICP nanoparticle vaporizing stage 1762-1766, (6) a nozzle1767, and (7) an extractor 1768. A vacuum pump 1746 exhausts spentgases.

The staged plasma system 1700 include cluster de-aggregator 1755followed by a spiral pre-heater 1756. Cluster de-aggregator 1755 servesto break up any nanopowder clusters in a dielectric barrier discharge,e.g., a multi-needle system powered from an RF generator 1757. Thepre-heater 1756 at the entrance the AP-ICP plasma system part 1720serves to (1) heat the argon carrier gas in order to prevent cooling ofthe top plasma torch, and (2) to lessen coupling between the dielectricbarrier discharge 1755 and the AP-ICP discharge 1761.

The etching-annealing part 1710 functionally includes: (1) a hydrogenchloride delivery 1770-1771, (2) a selector valve 1772, (3) a hydrogendelivery 1773-1777, (4) a plasma reactor 1778-1782, (5) a nozzle 1783,and (6) an extractor 1784. Air cooling should be included. Gas delivery1770-1772 provides for injection of 100% hydrogen chlorine into etchingplasma beam 1712.

A five-axis motion system 1790-1794 is under program control of a hub1795. Five-axis motion includes x-y-z motion, rotation, and tilt. (1)X—fine motion −8″ Serves for programming motion and alignment of theholes with plasma beam; (2) X—coarse motion −10″. Serves for programmingmotion of sample from etching zone to deposition one; (3) Y—motion −2″.Serves for programming motion and alignment of the holes with plasmabeam; (4) Z—motion 4″. Serves for aligning the surface of sample withfocal plane of the plasma optics; (5) Rotation—360-degree Serves forprogramming motion of sample from etching zone to deposition one; and(6) Tilt −10 degree to +35 degree Serves for oblique deposition of thenon-flat surfaces.

Two-staged AP-ICP system 1700 is very useful in the deposition of Y₂O₃.Top stage 1757-1761 has its plasma reactor surrounded by top saddleantenna 1760 which has an applied RF power of 700-watts at a frequencyof 27.12 MHz. It does the pre-melting of nanoparticles. Bottom stage1762-1766 has its plasma reactor and joined to the nozzle 1767 with anorifice of roughly one millimeter. This lower plasma reactor issurrounded by bottom saddle antenna 1765 and has an applied RF power 2.7kilowatts at a frequency of 13.56 MHz. This bottom stage 1766 providesfor vaporization of the pre-melted first stage nanoparticles. Nozzle1767 is joined to the bottom stage and serves to transition the plasmatorch generated in this stage into a thin supersonic plasma beam ofunder one millimeter and eject it into the atmosphere through theorifice.

Each plasma system 1710 and 1720 has an extractor 1784 and 1768 toelectrically focus plasma beams 1712 and 1722 on the inlets of theshowerhead passages. Each is equipped with lids 1737 and 1733 to sealuninvolved gas deposition plate passages during our plasma beampenetration process. Each lid is made from silicon wafer with holearound two millimeters, and is aligned with the orifice in nozzles 1783and 1767.

The general practice of plasma beam penetration of high aspect, smallholes is complicated by Debye layer that prevents such penetration. Theplasma beams dissipate in the inlets of passages. As shown herein, theDebye layer can be breached by generating an auxiliary plasma dischargewith an RF generator connected to mesh 1743 positioned under showerhead1740. Auxiliary discharge coupling with the Debye layer dissipates thespatial charge of this layer, and releases plasma beams 1722 and 1712 tocarry in etching radicals and vaporized nanoparticles.

Although particular embodiments of the present invention have beendescribed and illustrated, such is not intended to limit the invention.Modifications and changes will no doubt become apparent to those skilledin the art, and it is intended that the invention only be limited by thescope of the appended claims.

1. A plasma device, comprising: a plasma reactor that produces at leastone plasma beam; an extractor with an electric field that pulls theplasma beam from a nozzle in the plasma reactor and imparts a focus tothe plasma beam while directing and focusing the plasma beam into anentrance of a through-hole on a first surface of a workpiece; anauxiliary plasma reactor that generates a capacitively coupled plasma(CCP) discharge adjacent to a second opposite surface near an exit ofthe through-hole; wherein, each plasma beam is enabled thereby toovercome Debye sheathing congestion and completely penetrate thethrough-hole from the entrance to the exit by the CCP discharge; andwherein deposition materials, etchants, solvents, and/or heat arethereby rendered deliverable inside the entire length of thethrough-hole from entrance to exit.
 2. The plasma device of claim 1,wherein the plasma reactor comprises: an atmospheric pressure,inductively coupled plasma (AP-ICP) torch with an upper plasma reactorcoupled to a lower plasma reactor and comprising an upper quartzconfinement tube between a first pair of planar spiral-coil RF antennaspowered by a first source of radio frequency (RF) energy, and a lowerquartz confinement tube between a second pair of planar spiral-coil RFantennas powered by a second source of RF energy.
 3. The plasma deviceof claim 2, wherein the plasma reactor further comprises: an input thatreceives nanopowders that are pre-melted in the upper plasma reactor,and then vaporized in the lower plasma reactor, and then delivered inthe plasma beam through the nozzle and extractor and deposited to aninside wall of the through-hole in the workpiece.
 4. The plasma deviceof claim 1, wherein: the workpiece is an aluminum gas distribution platewith hundreds of through-holes as gas flow passages each on the order ofone millimeter in diameter; and wherein, the CCP discharge counteractsand undoes a Debye blockage of the gas flow passages within the aluminumgas distribution plate and drain them of Debye electron charge electronssuch that the focused plasma beam is enabled to completely penetrate theinside walls of the gas flow passages well enough to etch, clean, heat,deposit a coating from a nanopowder vapor, and anneal the coating insequence.
 5. The plasma device of claim 4, wherein the plasma reactorfurther comprises: a sheathing gas input; a selectable discharge gasinput that selects amongst argon, hydrogen, and hydrogen chloride tovariously support an etch, clean, heat, deposit, and anneal sequence. 6.The plasma device of claim 5, further comprising: a dielectric barrierdischarge device connected to de-aggregate yttrium oxide nanopowdersbefore they are input to the plasma reactor for a more effectivepre-melting by the upper plasma reactor and a more thorough vaporizationby the lower plasma reactor.
 7. The plasma device of claim 6, furthercomprising: a plurality of focused plasma beams simultaneously emittedin parallel in a linear array from the plasma reactor and extractor;wherein the plasma density and nanopowder vapor density of each of theplurality of focused plasma beams are balanced by the RF antennas andnanopowder inputs to produce simultaneously uniform plasma spots andrates of nanoparticle deposition within several gas flow passages atonce.
 8. An aluminum gas distribution plate refurbishment system,comprising: a plasma reactor that produces a plurality of plasma beamsand that includes an atmospheric pressure, inductively coupled plasma(AP-ICP) torch with an upper plasma reactor coupled to a lower plasmareactor and comprising an upper quartz confinement tube between a firstpair of planar spiral-coil RF antennas powered by a first source ofradio frequency (RF) energy, and a lower quartz confinement tube betweena second pair of planar spiral-coil RF antennas powered by a secondsource of RF energy; a nanopowder input that receives nanopowders thatare pre-melted in the upper plasma reactor, and then vaporized in thelower plasma reactor, and then delivered in the plasma beam through thenozzle and extractor and deposited to an inside wall of a correspondingthrough-hole in an aluminum gas distribution plate as gas flow passageseach on the order of one millimeter in diameter; a sheathing gas inputand a selectable discharge gas input selectable amongst argon, hydrogen,and hydrogen chloride gases to variously support etching, cleaning,heating, depositing, and annealing of inside walls of the gas flowpassages and in a sequence; a dielectric barrier discharge deviceconnected to de-aggregate yttrium oxide nanopowders before they areinput to the plasma reactor for a more effective pre-melting by theupper plasma reactor and a more thorough vaporization by the lowerplasma reactor; an extractor that pulls each plasma beam from a nozzlein the plasma reactor and imparts a focus to the plasma beam whiledirecting and focusing the plasma beam from above into an entrance of athrough-hole on a first surface an aluminum gas distribution plate; anauxiliary plasma reactor that generates a capacitively coupled plasma(CCP) discharge just beneath the aluminum gas distribution plateadjacent to a second opposite surface near an exit of the through-hole;wherein, the CCP discharge counteracts and unknots any Debye blockage ofthe gas flow passages within the aluminum gas distribution plate anddrain them of Debye electron charge electrons such that the focusedplasma beam is enabled to completely penetrate the inside walls of thegas flow passages well enough to etch, clean, heat, deposit a coatingfrom a nanopowder vapor, and anneal the coating in sequence; wherein,each plasma beam is enabled thereby to completely penetrate acorresponding through-hole from its entrance to its exit by contact withthe CCP discharge; wherein, a plasma density and a nanopowder vapordensity of each of the plurality of focused plasma beams are balanced byalterations to the RF antennas and nanopowder inputs to simultaneouslyproduce ultimately uniform plasma spots and rates of nanoparticledeposition within several gas flow passages.
 9. A method ofrefurbishment of an aluminum gas distribution plate workpiece,comprising; producing at least one plasma beam from a plasma reactor;pulling each plasma beam from a nozzle in the plasma reactor with anextractor plate that imparts a focus to the plasma beam while directingand focusing the plasma beams from above into an entrance of athrough-hole on a first surface an aluminum gas distribution plateworkpiece; generating a capacitively coupled plasma (CCP) discharge withan auxiliary plasma reactor just beneath the aluminum gas distributionplate workpiece adjacent to a second opposite surface near an exit ofthe through-hole; wherein, the plasma beam is enabled to completelypenetrate the through-hole from the entrance to the exit by the CCPdischarge.
 10. The Method of claim 9, further comprising: cleaning theinside walls of the gas flow passages of any contaminants of aprior-life PE-CVD process with plasma beams produced from hydrogenchloride gas (HCl); rinsing away the chemical reaction byproducts leftbehind by such HCl plasma cleaning with plasma beams formed from atomichydrogen; pre-heating the surfaces of the passage walls with plasmabeams formed from argon gas to better adhere a nanocoating of Yttriumoxide nanopowders in a Y₂O₃ vapor; exposing the surfaces of the passagewalls to a Y₂O₃ vapor carried in by plasma beams formed from argon gasto improve the gas distribution plates with plasma-chemical corrosionprotection; and annealing the deposited layers of Y₂O₃ nanopowders byheating from plasma beams formed from argon gas so the Y₂O₃ nanopowdersbetter adhere to the surfaces of the inside walls of the passages;wherein, the aluminum gas distribution plate workpiece is restored touseable service in another piece of semiconductor processing equipment.